On the night before Halloween, there will be no ghosts or goblins skulking about in How Evil Are You? (Discovery Channel, 9 p.m.), but that doesn’t make it any less disturbing. Hosted and produced by Hostel writer-director Eli Roth, the one-hour special – which is part of the Curiosity series – examines the nature of evil as the horror movie maven submits to a brain scan that measures his physiological responses to upsetting images (and compares them with those from potentially psychotic minds). As his pièce de résistance, though, he re-stages Yale Professor Stanley Milgram’s controversial 1961 experiment. (In the Milgram experiment, subjects were ordered to give a set of increasingly powerful electric shocks to people as punishment for answering questions incorrectly. The shocks weren’t real; Milgram was simply seeking to explore subjects’ limits on obeying authority, and the results weren’t always pretty.) In this clip, you’ll see a tease of what happens when Roth decides to put a new set of subjects in the hot (electric) seat to find out if we’re “better or worse than we were 50 years ago.” Press play or WE WILL ADMINISTER 450 VOLTS ALL OVER YOU. (Just kidding. It’s not even plugged in.)